Delta 6,7-taxols antineoplastic use and pharmaceutical compositions containing them

Abstract: This invention provides 7-deoxy-Δ 6,7 -taxol and 7-deoxy-Δ 6,7 -taxol analogs of Formula I: The compounds of Formula I are useful for the same cancers for which taxol has been shown active, including human ovarian cancer, breast cancer, and malignant melanoma as well as lung cancer, gastric cancer, colon cancer, head and neck cancer, and leukemia.

Description: Field of the Invention This invention relates to compounds and processes that are useful in the preparation of 10-deacetyltaxol, taxotere and analogues thereof. Background of the Invention Taxol and taxotere are potent anticancer agents. US-A-5248796 relates to 10-desacetoxy-11,12-dihydrotaxol-10,12(18)-diene derivatives and the preparation of 10-desacetoxytaxol. EP-A-0428376 discloses the utilisation of compounds 3 (see Chart A', below), by protection ofthe hydroxy group, hydrolysis ofthe ester to the acid, and condensation directly with a baccatin derivative or after conversion to the oxazinone. These procedures require large excesses of the acylating agent and generally do not proceed beyond about 60% completion. Procedures have also been described using a beta-lactam intermediate, but these also require large excesses of reagent or the introduction of very strong bases such as LDA which makes them more difficult to perform and unsuitable for certain analogues (Ojima et al , J. Org. Chem., 1991, 56 , 1681; and EP-A-0400971). A very effective condensation procedure involving the conversion ofthe hydroxyamine derivative 3 to an oxazolidine with 2 non-hydrogen substituents at the 2 position is described by Commerçon et al , Tetrahedron Lett., 1992, 33 , 5185, and in WO-A-92/09589. The condensation proceeds in very high yield, but the removal of the protecting group requires sufficiently strong acid that sensitive taxol analogues are destroyed under the deprotection conditions. Summary of the Invention The present invention is compounds 5, 6 and 9 (Chart A'), and the processes 3 + 4/4A → 5 and 7 + 8 → 9. The variable groups in the relevant compounds, and certain preferred features, are defined in the claims. Description of the Invention Referring to Chart A', the 3-azido-2-hydroxy-carboxylic acid esters 1 may be prepared as described in the literature (see Denis et al , J. Org. Chem., 1990, 55 , 1957). These materials are readily hydrogenated to the free amines 2, even though the literature intentionally avoids this intermediate by preparing the hydroxy-acylated intermediate prior to the reduction of the azide. The amine 2 is sufficiently stable that no problem is encountered in isolating and directly using it to prepare the N-acylated free hydroxy compounds 3 . A feature of this invention is utilisation of compounds 3 to form oxazolidines 5, not with a ketone, as described in the prior art, but with an electron-rich benzaldehyde 4 . The oxazolidines derived from the benzaldehyde 4 are produced as a mixture of diastereomers but that have been separated in some cases. The diastereomers have been shown to be equally useful when carried on in the synthesis. The oxazolidines 5 are readily hydrolysed to the salts 6 and the acids 7 . The acid is labile and needs to be used shortly after preparation. Both oxazolidine isomers are equally effective in the condensation reaction with the protected baccatins 8, giving an excellent yield of the oxazolidine-protected taxol analogues 9 . More importantly, both oxazolidine isomers from these electron-rich benzaldehydes are readily hydrolysed under very mild acid conditions, allowing deprotection without causing undesired transformations of highly acid-sensitive taxol derivatives such as 10 or the Δ 6,7 -taxol analogues which are the subject of EP-B-0703909. The deprotection may be carried out such that both the oxazolidine and the 7-protected hydroxyl of 9 are removed at the same time or each may be removed independently. The product ( 10 MZ ) shown in Chart A' may be converted by procedures described in EP-B-0703909 and EP-B-0982301. More particularly, the conversion of azide 1 to the amine 2 is effected by reduction as is known in the art. Thus, the reaction may be carried out by hydrogenation in the presence of a variety of hydrogenation catalysts such as palladium, platinum, rhodium or ruthenium. Alternatively, the azide may be reduced by treatment with a phosphine such as triphenyl or tributyl phosphine or by an acid such as hydrochloric, sulfuric, trifluoroacetic or hydrobromic in the presence of a metal such as zinc, iron, or tin. These reactions may be effected in a solvent such as ethanol, methanol, ethyl acetate, methyl t-butyl ether or tetrahydrofuran and the like. The conversion of amine 2 to its acylated derivative 3 is effected by treatment of the amine in pyridine or a non basic solvent such as methylene chloride or tetrahydrofuran containing a tertiary amine such as triethyl amine or ethyl diisopropyl amine with an acylation agent. If 3 is a urethane, 2 is treated with an agent such as benzylchloroformate, 2,2,2-trichloroethoxycarbonyl chloride, di-tert-butyldicarbonate, or other urethane forming agent as is known in the art. If 3 is an amide, 2 is treated with an acylating agent such as an acyl halide, and acyl anhydride, or other acylating agent as is known in the art. If 3 is a urea or a thiourea, 2 is treated with an agent such as alkyl or aryl isocyanate, alkyl or aryl isothiocyanate, or other urea or thiourea forming agent as is known in the art. The hydroxy amide or urethane 3 is converted to the oxazolidine 5 by treatment with an electron rich benzaldehyde or its acetal such as dimethyl or diethyl acetal 4 and an acid catalyst such as p-toluene sulfonic acid, pyridinium p-toluene sulfonate or other acid catalysts known in the art in a solvent such as tetrahydrofuran, toluene, methylene chloride, or other aprotic solvent. Examples of electron rich benzaldehydes include but are not limited to 2-, 3-, 4-methoxybenzaldehyde; 2,4-, 3,5-, 2,5-dimethoxybenzaldehyde; 2,4,6-trimethoxybenzaldehyde; and 4-ethoxybenzaldehyde. The preferred benzaldehyde is 2,4-dimethoxybenzaldehyde. The oxazolidine formation is generally carried out by heating to reflux to distill both the solvent and to carry off the evolved water or alcohoL The ester of 5 is hydrolyzed to the salt 6 by treatment with an alkali or quaternerary amine hydroxide or by an alkali carbonate or other base as known in the art in a solvent such as water, methanol, ethanol, or other protic solvent. The reaction may by carried out from -78°C to 100°C. The product 6 is stable and may be isolated by evaporation of the solvents and stored as a solid or the reaction may be used directly to convert 6 to the acid 7 by treatment with acid. Generally, 7 is obtained by treating an aqueous solution of 6 in a separatory funnel with sufficient acid such as hydrochloric, sulfuric, potassium hydrogen sulfate, or the like, and partitioning the desired acid into an organic solvent such as ethyl acetate, methylene chloride, ether, or the like and evaporation of the solvent. The resultant acid 7 is sufficiently pure and stable for use in the next reaction but in general is not sufficiently stable for long term storage. The acid 7 is condensed with the baccatin derivative 8 to form the ester 9 with a dehydrating agent. Most preferred for this procedure is a carbodiimide such as dicyclohexyl carbodiimide, diisopropyl carbodiimide, di-p-tolyl carbodiimide, ethyl dimethylaminopropyl carbodiimide hydrochloride salt, or the like, and a basic catalyst, preferably 4-dimethylaminopyridine. The reaction is generally carried out in an aprotic solvent such as toluene, benzene, tetrahydrofuran, dioxane, or the like at 25°C to 100°C. Other dehydration procedures for the formation of 9 may be used such as conversion of 7 to its mixed ester with a sulfonic acid such as with toluenesulfonyl chloride or benzenesulfonyl chloride, or formation of the acid halide from the dried 6 in the presence of oxalyl chloride as is known in the art for acid sensitive carboxylic acids. The oxazolidines 9 may be deprotected so that the protecting oxazolidine and the groups blocking the hydroxyl at the baccatin 7 position are individually removed in either order or both removed together depending on the protecting group at the 7 position and on the reaction conditions. If R 14 is an acid labile group such as a silyl ether, then hydrolysis of the oxazolidine may be nm under mild acid conditions and leads to the 7 position deprotection as well, giving 10MZ directly. Conditions for such conversions include hydrolysis in aqueous acetic acid, aqueous alcoholic acid of 0.01 to 0.1 N at 0°C to 50°C, or alcoholic acid of 0.01 to 0.1 N at 0°C to 50°C. Alternatively, the protection at the 7 position could be removed at a second step if it is not acid labile. Preparation 1 : Preparation of (2R,3S)-β-phenyl isoserine methyl ester (2) The (2R,3S)-3-azido-2-hydroxy-3-phenylpropionic acid methyl ester (1, 0.5 g) is hydrogenated over 10% palladium on carbon (0.1 g) in ethanol at atmospheric pressure for 1 hour. The reaction is filtered and evaporated to yield the desired amine. Mp 106-108°C. NMR(CDCl 3 , TMS): δ 2.1 (bs); 3.80 (s, 3H); 4.31 (m, 2H); 7.28-7.45 (m, 5H). Preparation 2 : Preparation of (4S,5R)-N-Benzoyl-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid methyl ester ( 5Aa & 5Ab ) N-Benzoyl-β-phenyl isoserine methyl ester ( 3A, 0.5 g, 1.67 mM) is dissolved in dry THF (10 mL) and benzene (10 mL) and the solution treated with 2,4-dimethoxy benzaldehyde dimethyl acetal ( 4 , 0.420 g, 1.98 mM) and pyridinium p-toluenesulfonate (12 mg) and the solution warmed to reflux. After 30 minutes the reaction is cooled to RT and allowed to stand overnight. It is then again warmed to slowly distill off 1/2 of the solvent over 1 hr. TLC shows the reaction to be finished at this point. The reaction is concentrated in vacuo and the residue chromatographed over 50 g silica gel packed in (5-95) methanol-toluene. The column is eluted with methanol-toluene (5-95). Fractions of 12 mL are collected. The product elutes as a mixture. Thus, fractions containing both 5Aa & 5Ab are recombined and evaporated. The residue (0.90 g) is rechromatographed over silica gel (100 g) The column is eluted with ethyl acetate-toluene (500 mL of 15-85 and 500 mL of 20-80). Fractions of 20 mL are collected and analyzed by TLC. The fractions containing each 5Aa & 5Ab are combined and evaporated under vacuum. less polar isomer 5Aa mixture of less polar and more polar isomers 5Aa and 5Ab more polar 5Ab Isomer 5Ab is crystallized from EtOAc to give white crystals (142 mg, mp 138-141°C). Data for 5Aa: TLC: silica gel; 20% EtOAc-80% toluene; R f : 0.50 1 H NMR (CDCl 3 ; TMS): δ; 3.69 (s, 3H); 3.77 (s, 3H); 3.86 (s, 3H); 4.93 (d, 1H); 5.6 (brs, 1H); 6.28-6.37 (m, 2H); 6.90 (s, 1H); 7.03 (d, 1H); 7.15-7.55 (m, 9);. Data for 5Ab: TLC: silica gel; 20% EtOAc-80% toluene; R f : 0.41. 1 H NMR (CDCl 3 ; TMS): δ 3.62 (bs, 3H); 3.75 (brs, 6H); 4.65 (d, 1H); 5.68 (bs, 1H); 6.2-6.5 (m, 2H); 6.8-7.55 (m, 11H). UV: EtOH; 229 (16,000), 277 (3,240), 281sh (3,170). Elemental analysis: Calculated: C 69.79; H 5.63; N 3.13. Found: C 69.61; H 5.61; N 2.93. Preparation 3 : Preparation of (4S,5R)-N-benzyl-2-(2,4 dimethoxyphenyl)-4-phenyl-5-oxazolidine carboxylic acid potassium salt. 6Ab (4S,5R)-N-benzyl-2-(2,4 dimethoxyphenyl)-4-phenyl-5-oxazolidine carboxylic acid methyl ester (Preparation 2, 5Ab , 355mg,0.79mM) is dissolved in 9ml methanol. To the solution is added water (350µl) and potassium carbonate (155mg, 1.12mM). After stirring 5 hours no solids remain and TLC indicates very little methyl ester remaining. The solvent is concentrated in vacuo and water (10ml) added to the oil. The solution is freeze dried leaving 500mg fluffy white powder which contains 374mg of the potassium salt. TLC: silica gel 60; 1:2 EtOAc:Hexane; R f : origin. Preparation 4 : Preparation of 7-TES-baccatin III-13-(4S,5R)-N-Benzoyl-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester ( 9AbA ) A solution of (4S,5R)-N-benzoyl-2-(2,4 dimethoxyphenyl)-4-phenyl-5-oxazolidine carboxylic acid potassium salt ( 6Ab , Preparation 3, 91.4 mg, approximately 0.15 mM) in ethyl acetate is washed with 5% aqueous NaHSO 4 . The ethyl acetate solution is dried and evaporated leaving the corresponding acid 7Ab. The residue is dissolved in methylene chloride (0.8 ml) and toluene (1.75 ml), and combined with 7-triethylsilyl-baccatin III (68 mg). The mixture is treated with 4-dimethylaminopyridine (6.3 mg) and 1,3-dicyclohexylcarbodiimide (34 mg). The reaction is heated to 80 C for 90 minutes, cooled, filtered, and chromatographed on silica gel in ethyl acetate-hexane mixtures. An 86% yield of the coupled product 9AbA was obtained. NMR (CDCl 3 , TMS): 8 0.58 (m, 6H); 0.90 (m); 1.73 (s, 3H); 1.87 (m,1H); 2.03 (m,3H); 2.17 (bs,3H); 2.20 (s,3H); 2.23 (m,2H); 2.50 (m, 1H); 3.78 (bs, 3H); 3.80 (s, 3H); 3.85 (d, 1H); 4.13 (d, 1H); 4.27 (d, 1H); 4.50 (m, 1H); 4.90 (m, 2H); 5.63 (bs, 1H); 5.68 (d, 1H); 6.25-6.48 (m, 3H); 6.50 (s, 1H); 6.86 (s, 1H); 7.09 (m, 1H); 7.15-7.65 (m, 13H); 8.05 (d, 2H). Preparation 5 : Preparation of Taxol (Compound 10AA ) 7-TES-baccatin III-13-(4S,5R)-N-Benzoyl-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester ( 9AbA ) is deprotected by stirring in 0.1 M HCl in methanol for 10 minutes. After diluting with ethyl acetate, the solution is washed with 5% NaHCO 3 , dried and evaporated. The product is purified by column chromatography on silica gel in acetone-hexane mixtures. The proton and carbon NMR data are identical with natural taxol. Preparation 6 : Preparation of (4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinocarboxylic acid methyl ester ( 5Ba,& 5Bb ) N-Boc-β-phenyl isoserine methyl ester ( 3B ) (0.5 g, 1.69 mM) is dissolved in dry THF (10 mL) and toluene (10 mL) and concentrated to dryness to remove any water of crystallization. The residue is then dissolved in dry THF (10 mL) and the solution treated with 2,4-dimethoxy benzaldehyde dimethyl acetal (4) (0.425 g, 2.0 mM) and pyridinium p-toluenesulfonate (12 mg) and the solution warmed to reflux. After 30 minutes the reaction is cooled to RT and allowed to stand overnight. It is then again warmed to reflux for 3 hours. The reaction is checked by TLC and is found to be incomplete. The reaction is then heated to 85°C to distill off about 2/3 of the THF. Then fresh THF (10 mL) and acetal (200 mg) is added and the reaction refluxed another 2 hours. TLC shows the reaction to be finished at this point. The reaction is concentrated in vacuo and the residue chromatographed over 100 g silica gel packed in (15-85) acetone-hexane. The column is eluted with acetone-hexane (500 mL of 15-85 and 500 mL of 20-80). Fractions of 20 mL are collected. The desired product isomers elute as a mixture. The fractions containing the mixture of 5Ba, & 5Bb and are combined and concentrated in vacuo leaving a white foam. The foam is rechromatographed over 100 g silica gel packed and eluted with (10-90) EtOAc-toluene. Fractions of 20 mL are collected and analyzed by TLC. There is thus isolated 34 mg of the less polar isomer 5Ba, 187 mg of a mixture of less polar and more polar isomers 5Ba and 5Bb, and 500 mg of the more polar isomer 5Bb. Isomer 5Bb is crystallized from EtOAc-hexane to give white crystals (378 mg). The mixture of isomers is also crystallized from EtOAc-hexane to give crystalline 5Bb (113 mg) of similar purity by TLC as the mother liquors from the isomer 5Bb crystallization. These crystals and the mother liquors are therefore combined and recrystallized from EtOAc-hexane to give more pure 5Bb (160 mg). Data for 5Ba: TLC: silica gel 60 ; 10% EtOAc-90% toluene; R f : 0.44. 1 H NMR-(CDCl 3 ; TMS): δ 1.26 (s, 9H); 3.80 (s, 3H); 3.84 (s, 3H); 3.85 (s, 3H); 4.86 (d, 1H); 5.24 (s, 1H); 6.40 (dd, 1H); 6.47 (d, 1H); 6.72 (s, 1H); 7.12 (d, 1H); 7.30-7.43 (m, 3H); 7.53 (d, 2H). Data for 5Bb: TLC: silica gel 60 ; 10% EtOAc-90% toluene; R f : 0.38. 1 H NMR (CDCl 3 ; TMS): δ 1.10 (s, 9H); 3.52 (bd, 3H); 3.81 (s, 3H); 3.87 (s, 3H); a4.54 (d, 1H); 5.43 (bs, 1H); 6.48 (s, 2H); 6.81 (bs, 1H); 7.13 (bs, 1H); 7.30-7.48 (m, 5H). UV: EtOH; 233 (10,600), 260sh (1010), 277 (2840), 281sh (2680). Elemental analysis: Calculated: C 65.00; H 6.59; N 3.16. Found: C 64.86; H 6.42; N 3.24. Preparation 7 : Preparation of (4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid potassium salt ( 6Ba ) and its free acid 7Ba A 100 mg (0.23 mM) quantity (4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid methyl ester (Preparation 6, 5Ba ) is stirred at room temperature under nitrogen in 3 mL MeOH. Added 0.1 mL water and 43 mg (031 mM) potassium carbonate. After 1 hour, TLC shows no starting material left. Stored in freezer overnight. The next morning the solvent is evaporated to give (4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid potassium salt ( 6Ba ). The residue is partitioned between methylene chloride and water containing 0.9 mL IN HCl. The layers are separated and the aqueous layer reextracted with methylene chloride. The organic layers are combined, dried over sodium sulfate and evaporated. This leaves (4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ( 7Ba ) as a white solid. TLC (silica gel 60): 20% EtOAc-80% hexane-2% HOAc: Rf: 0.07 1 H NMR (CDCl 3 ; TMS): δ 1.26 (s, 9H); 3.76 (s, 6H); 4.77 (s, 1H); 5.34 (s.1H); 6.33-6.45 (d, 2H); 6.60 (s, 1H); 7.07-7.16 (d, 1H); 7.24-7.40 (m, 3H); 7.42-7.54 (d, 2H). Preparation 8 : Preparation of 7-TES-baccatin III-13-(4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester ( 9BaA ) A 0.23 mM quantity (4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid (Preparation 7 , 7Ba ) is dissolved in 1.5 mL methylene chloride-3 mL toluene. To this is added 106 mg (0.15 mM) 7-TES-baccatin III ( 8A ), 11 mg (0.09 mM) DMAP and 49 mg (0.24 mM) DCC. The reaction is stirred under nitrogen and heated to 75°C for 90 minutes then cooled to RT. The resultant urea side product is removed by filtration and the filtrate is evaporated under vacuum. The residue is chromatographed over 20 g silica gel, eluting with 30-70 EtOAc-hexane. Fractions of 5 mL are collected, analyzing them by TLC. Fractions 17-34 contain the desired product and are combined and evaporated. 7-TES -baccatin III-13-(4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester ( 9BaA ) is obtained as a white solid. TLC: silica gel 60; 30% EtOAc-70% hexane; Rf: 0.56 Mass Spec (FAB, m / z ) 1112, 1012, 874, 328, 284, 115, 105, 87. 1 H NMR (CDCl 3 ; TMS): δ 0.52-0.66 (m, 6H); 0.85-1.00 (m, 9H); 1.80-1.93 (m, 1H); 2.15 (s, 3H); 2.20 (s, 3H); 2.21-2.30 (m, 1H); 2.40-2.54 (m, 1H); 3.82 (s, 3H); 3.87 (s, 3H); 3.81 (d, 1H); 4.10 (d, 1H); 4.26 (d, 1H); 4.49 (m, 1H); 4.83-4.93 (m, 2H); 5.31 (d, 1H); 5.67 (d, 1H); 6.29 (t, 1H); 6.38-6.53 (m, 3H); 6.69 (s, 1H); 7.13 (d, 1H); 7.29-7.65 (m, 8H); 8.05 (d, 2H). Preparation 9 : Preparation of 13-(N-Boc-β-phenyl isoserinyl)- baccatin III ( 10BA ) A 0.1 M HCl solution is prepared from 0.071 mL acetyl chloride and 9.929 mL of MeOH, leaving it sit for 30 minutes before using. To 57 mg (0.051 mM) 7-TES -baccatin III-13-(4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester (Preparation 8, 9BaA ) is added 0.5 mL of the above methanolic HCl solution with stirring under nitrogen. The reaction is complete after 75 minutes as shown by TLC. The reaction mixture is partitioned between ethyl acetate-5% sodium bicarbonate. The layers are separated and the aqueous layer reextracted with ethyl acetate. The organic layers are combined, dried over sodium sulfate and evaporated under vacuum. The crude product is chromatographed over 10 g silica gel, eluting with 50-50 ethyl acetate-toluene. Fractions of 2mL are collected, analyzing them by TLC. Pure product is found in fractions 19-42, which are combined and evaporated. 13-(N-Boc-β-phenyl isoserinyl)-baccatin III ( 10BA ) is obtained as a white solid. TLC: silica gel 60; 50-50 EtOAc-toluene; Rf: 0.38. Mass Spec (FAB): (M+H) measured at 850.3680; theory for C 45 H 56 N 1 O 15 is 850.3650; m / z 794, 569, 509, 105, 57. 1 H NMR (CDCl 3 , TMS): δ 1.14 (s, 3H); 1.27 (s, 3H); 1.33 (s, 9H); 1.67 (s, 3H); 1.84 (s, 3H); 2.24 (s, 3H); 2.38 (s, 3H); 3.44 (d, 1H); 3.81 (d, 1H); 4.17 (d, 1H); 4.30 (d, 1H); 4.41 (m, 1H); 4.63 (bs, 1H); 4.95 (d, 1H); 5.26 (bd, 1H); 5.43 (bd, 1H); 5.67 (d, 1H); 6.23 (t, 1H); 6.28 (s, 1H); 7.27-7.45 (m, 5H); 7.50 (t, 2H); 7.62 (t, 1H); 8.11 (d, 2H). Preparation 10 : Preparation of (4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid Potassium Salt ( 6Bb ) A solution of (4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid methyl ester (Preparation 6; 5Bb, 374 mg, 0.84 mM) in MeOH (11 mL) is stirred at RT under nitrogen and treated with water (0.37 mL) and potassium carbonate (161 mg, 1.17 mM). After 2 hours, TLC indicates the reaction to be about 70% done. After stirring overnight, the reaction is found to be complete. The solvent is evaporated and the residue dissolved in 10 mL water and freeze dried. This left 507 mg fluffy white solid, which contains (4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid Potassium Salt ( 6Bb, 393 mg). TLC: silica gel; 20% EtOAc-80% hexane; R f : origin. Preparation 11 : Preparation of 7-TES -baccatin III-13-(4S,5R)-N-Boc-2-(2,4-dimethoxy-phenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester ( 9BbA ) A 0.12 mM quantity of crude (4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid potassium salt (Preparation 10, 6Bb ) is partitioned between ethyl acetate-5% sodium bisulfate. The layers are separated and the aqueous layer reextracted with ethyl acetate. The organic layers are combined, dried over sodium sulfate and evaporated under vacuum. The resulting acid 7Bb is dissolved in 0.8 mL methylene chloride-1.5 mL toluene along with 53 mg (0.076 mM) of 7-TES-baccatin III ( 8A; See Denis, J.-N.; Greene, A. E.; Guénard, D.; Guéritte-Vogelein, F.; Mangatal, L.; Potier, P. J. Am . Chem . Soc. 1988, 110 , 5917.), 6 mg (0.049 mM) 4-dimethylaminopyridine (DMAP) and 25 mg (0.12 mM) dicyclohexylcarbodiimide (DCC). The reaction is stirred under nitrogen and heated to 75°C for 90 minutes. Cooled to RT and filtered off the urea side product. The filtrate is evaporated under vacuum. The residue is chromatographed over 15 g silica gel, eluting with 30-70 EtOAc-hexane. Collected 7 mL fractions, analyzing them by TLC. Fractions 16-38 contain the product and are combined and evaporated. 7-TES -baccatin III-13-(4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester ( 9BbA ) is obtained as a white solid. TLC: silica gel 60; 30% EtOAc-70% hexane; Rf: 0.33 Mass Spec (FAB, m / z ) 1112, 1012, 384, 328, 284, 115, 105, 87, 57. 1 H NMR (CDCl 3 ; TMS): δ 0.50-0.61 (m, 6H); 0.84-0.97 (m, 9H); 1.08 (s, 9H); 2.21 (s, 3H); 3.67 (d, 1H); 3.80 (s, 3H); 3.90 (s, 3H); 4.07 (d, 1H); 4.23(d, 1H); 4.40 (m, 1H); 4.53 (bd, 1H); 4.87 (d, 1H); 5.44 (bd, 1H); 5.60 (d, 1H); 6.34 (s, 1H); 6.44 (bs, 1H); 6.48 (s, 1H); 7.20 (bs, 1H); 7.30-7.50 (m, 7H); 7.60 (t, 1H); 8.01 (d, 2H). Preparation 12 : Preparation of 13-(N-Boc-β-phenyl isoserinyl)- baccatin III (10BA) A 0.1 M HCl solution is prepared from 0.071 mL acetyl chloride and 9.929 mL of MeOH, leaving it sit for 30 minutes before using. To 45 mg (0.040 mM) 7-TES-baccatin III-13-(4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester (Preparation 11, 9BbA ) is added 0.395 mL of the above methanolic HCl solution with stirring under nitrogen. The reaction is complete after 20 minutes as shown by TLC. After 30 minutes the reaction mixture is partitioned between ethyl acetate-5% sodium bicarbonate. The layers are separated and aqueous layer reextracted with ethyl acetate. The organic layers are combined, dried over sodium sulfate and evaporated under vacuum. The crude product is chromatographed over 5 g silica gel, eluting with 50-50 ethyl acetate-toluene. Fractions of 5 mL are collected and analyzed by TLC. Pure product is found in fractions 5-12 which are combined and evaporated. 13-(N-Boc-β-phenyl isoserinyl)- baccatin III (10BA) is obtained as a white solid. TLC: silica gel 60; 50-50 EtOAc-toluene; Rf: 0.42 1 H NMR (CDCl 3 , TMS): δ 1.15 (s, 3H); 1.27 (s, 3H); 1.33 (s, 9H); 1.68 (s, 3H); 1.85 (s, 3H); 2.25 (s, 3H); 2.38 (s, 3H); 3.44 (d, 1H); 3.80 (d, 1H); 4.17 (d, 1H); 430 (d, 1H); 4.41 (m, 1H); 4.62 (bs, 1H); 4.95 (d, 1H); 5.26 (bd, 1H); 5.43 (bd, 1H); 5.67 (d, 1H); 6.23 (t, 1H); 6.29 (s, 1H); 7.13-7.45 (m, 5H); 7.49 (t, 2H); 7.62 (t, 1H); 8.11 (d, 2H). Preparation 13 : Preparation of 7-(2,2,2-trichloroethoxycarbonyl)-baccatin III-13-(4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester ( 9BaB, 9BbB ) A 0.39 mM quantity of (4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid potassium salt ( 6Ba, 6Bb ) is partitioned between ethyl acetate-5% sodium bisulfate. The layers are separated and the aqueous layer reextracted with ethyl acetate. The organic layers are combined, dried over sodium sulfate and evaporated under vacuum. The residual acid 7Ba,7Bb is dissolved with stirring under nitrogen in 2 mL methylene chloride-6 mL toluene. To this is added 187 mg (0.245 mM) 7-(2,2,2-trichloroethoxycarbonyl)-baccatin III ( 8B, See for example Mangatal, L.; Adeline, M.-T.; Guenard, D.; Gueritte-Vogelein, F.; Potier, P. Tetrahedron 1989, 45 , 4177.), followed by 22 mg (0.18 mM) DMAP and 80 mg (0.39 mM) DCC. Soon after everything goes into solution, the urea side product starts to precipitate. Heat to 80°C for 70 minutes, following the reaction by TLC. After cooling to room temperature, the solid is filtered off and the filtrate evaporated under vacuum. The crude product is chromatographed over 50 g silica gel, eluting with 400 mL 30-70, 200 mL 40-60, 100 mL 70-30 ethyl acetate-hexane. Fractions of 15 mL are collected, analyzing them by TLC. The following fractions are combined and evaporated under vacuum to give white solids. Fr 14-20, less polar isomer 9BaB Fr 21-26, mixed isomers 9BaB, 9BbB Fr 27-32, more polar isomer 9BbB Fr 37-44, recovery of starting alcohol 8B Data for isomer 9BaB: TLC: silica gel 60; 40-60 ethyl acetate-hexane; Rf: 0.67. 1 H NMR (CDCl 3 , TMS) δ 1.26 (s); 1.82 (s, 3H); 2.12 (s, 3H); 2.19 (s, 3H); 2.58 (m, 1H); 3.81 (s, 3H); 3.91 (s, 3H); 3.97 (d, 1H); 4.13 (d, 1H); 4.28 (d, 1H); 4.66 (d, 1H); 4.92 (m, 2H); 5.03 (d, 1H); 5.36 (d, 1H); 5.63 (m, 1H); 5.67 (d, 1H); 6.32 (m, 1H); 6.40 (s, 1H); 6.51 (d, 1H); 6.69 (s, 1H); 7.16 (d, 1H); 7.37-7.62 (m, 8H); 8.02 (d, 2H). Data for isomer 9BbB: TLC: silica gel 60; 40-60 ethyl acetate-hexane; Rf: 0.55. 1 H NMR (CDCl 3 , TMS) δ 2.17 (bs); 3.47 (m); 3.79-3.94 (m); 4.08 (d); 4.27 (d); 4.54 (m); 4.65 (m); 4.89 (d); 5.01 (m); 5.40 (m); 5.50 (m); 5.62 (d); 6.24 (bs); 6.49 (bs); 7.37-7.65 (m); 8.03 (d). Preparation 14 : Preparation of 7-(2,2,2-trichloroethoxycarbonyl)-13-(N-Boc-β-phenyl isoserinyl)-baccatin III 10BB A 0.1M HCl solution in MeOH is prepared from 0.071 mL acetyl chloride and 9.929 mL MeOH and left standing for 30 minutes before using. A 252 mg (0.216 mM) quantity of 7-(2,2,2-trichloroethoxycarbonyl)-baccatin III-13-(4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester (Preparation 13; 9BaB,9BbB ) is stirred at RT under nitrogen with 2.2 mL of the above 0.1 M HCl solution in MeOH. The reaction is followed by TLC and since it is incomplete after 20 minutes, another 0.5 mL HCl solution is added and the reaction continued for 15 minutes. The reaction mixture is then diluted with ethyl acetate and washed with 5% sodium bicarbonate. The layers are separated and the aqueous layer reextracted with ethyl acetate. The organic layers are combined, dried over sodium sulfate and evaporated under vacuum. The crude product is chromatographed over 30 g silica gel, eluting with 200 mL 35-65 and 300 mL 40-60 ethyl acetate-hexane. Fractions of 5 mL are collected, analyzing them by TLC. Fractions 25-54 contain the pure product and are combined and evaporated under vacuum to give 7-(2,2,2-trichloroethoxycarbonyl)-13-(N-Boc-β-phenyl isoserinyl)-baccatin III 10BB, as a white solid. TLC: silica gel 60; 40-60 ethyl acetate-hexane; Rf: 0.36 Mass Spec (FAB, m / z ) (M+H) at 1024, 1026, 1028; (M+H) measured at 1024.2656; theory for C 48 H 57 Cl 3 N 1 O 17 is 1024.2692; 1024, 968, 924, 743, 683, 105, 57. 1 H NMR (CDCl3, TMS) δ 1.17 (s, 3H); 1.24 (s, 3H); 1.34 (s, 9H); 1.83 (s, 3H); 1.91 (s, 3H); 2.17 (s, 3H); 2.39 (s, 3H); 2.62 (m, 1H); 3.60 (d, 1H); 3.94 (d, 1H); 4.16 (d, 1H); 4.30 (d, 1H); 4.63 and 5.04 (2d, 2H); 4.62 (bs, 1H); 4.95 (d, 1H); 5.26 (bd, 1H); 5.45-5.60 (m, 2H); 5.66 (d, 1H); 6.20 (t, 1H); 6.36 (s, 1H); 7.24-7.44 (m, 5H); 7.49 (t, 2H); 7.61 (t, 1H); 8.08 (d, 2H). Preparation 15 : Preparation of 13-(N-Boc-β-phenyl isoserinyl)-baccatin III ( 10BA ) and 7-(2,2-dichloroethoxycarbonyl)-13-(N-Boc-β-phenyl isoserinyl)-baccatin III 10BG. A 150 mg (0.146 mM) quantity of 7-(2,2,2-trichloroethoxycarbonyl)-13-(N-Boc-β-phenyl isoserinyl)-baccatin III (Preparation 14, 10BB ) is stirred at RT under nitrogen in 13.5 mL MeOH and 1.5 mL HOAc. To this is added 150 mg activated zinc and the reaction heated to 50°C for 60 minutes. The reaction is followed by TLC and adding 4 more 150 mg portions of zinc, heating for 45 minutes after each addition. The reaction mixture is filtered and the filtrate evaporated under vacuum. The residue is partitioned between methylene chloride-water. The layers are separated and the aqueous layer backextracted with methylene chloride. The organic layers are combined, dried over sodium sulfate and evaporated. The crude product is chromatographed over 20 g silica gel, eluting with 200 mL 60-40 and 200 mL of 70-30 ethyl acetate-hexane. Fractions of 5 mL are collected, analyzing them by TLC. The following fractions are combined and evaporated to give white solids. Fr 9-13, 7-(2,2-dichloroethoxycarbonyl)-13-(N-Boc-β-phenyl isoserinyl)-baccatin III 10BG. Fr 14-44, 13-(N-Boc-β-phenyl isoserinyl)-baccatin III ( 10BA ) Data for 7-(2,2-dichloroethoxycarbonyl)-13-(N-Boc-β-phenyl isoserinyl)-baccatin III 10BG TLC: silica gel 60; 50-50 ethyl acetate-hexane; Rf: 0.81 (this product and starting material nm together in this TLC system). 1 H NMR: (CDCl 3 , TMS) 8 1.17 (s, 3H); 1.24 (s, 3H); 1.35 (s, 9H); 1.61 (s, 3H); 1.81 (s, 3H); 2.19 (s, 3H); 2.39 (s, 3H); 2.52-2.68 (m, 1H); 3.37 (d, 1H); 3.92 (d, 1H); 4.16 (d, 1H); 4.32 (d, 1H); 4.53 (m, 2H); 4.63 (bs, 1H); 4.95 (d, 1H); 5.26 (bd, 1H); 5.40 (bd, 1H); 4.48 (m, 1H); 5.67 (d, 1H); 5.96 (m, 1H); 6.20 (t, 1H); 6.45 (s, 1H); 7.28-7.44 (m, 5H); 7.50 (t, 2H); 7.62 (t, 1H); 8.10 (d, 2H). Data for 10BA: TLC: silica gel 60; 50-50 ethyl acetate-hexane; Rf: 0.32 1 H NMR: (CDCl 3 , TMS) δ 1.14 (s, 3H); 1.24 (s, 3H); 1.32 (s, 9H); 1.67 (s, 3H); 1.84 (s, 3H); 2.23 (s, 3H); 2.37 (s, 3H); 2.44-2.59 (m, 1H); 2.64 (bd, 1H); 3.70 (bs, 1H); 3.78 (d, 1H); 4.15 (d, 1H); 4.28 (d, 1H); 4.40 (m, 1H); 4.61 (bs, 1H); 4.94 (d, 1H); 5.25 (bd, 1H); 5.57 (bd, 1H); 5.65 (d, 1H); 6.22 (t, 1H); 6.29 (s, 1H); 7.24-7.44 (m, 5H); 7.48 (t, 2H); 7.60 (t, 1H); 8.08 (d, 2H). Preparation 16 : Preparation of 7,10-bis-Troc-baccatin III-13-(4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester ( 9BbC ) Crude (4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid potassium salt (Preparation 10; 6Bb ) (0.089 mM) is partitioned between EtOAc- 5% NaHSO 4 . The layers are separated and the aqueous layer reextracted with EtOAc. The organic layers are combined, dried over sodium sulfate and evaporated under vacuum leaving (4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ( 7Bb ). This residue is stirred at room temperature under nitrogen in methylene chloride (0.8 mL) and toluene (1.5 mL). To this is added 7,10-bis-Troc-10-deacetyl baccatin III ( 8C, see for example Senilh, V.; Gueritte-Vogelein, F.; Guenard, D.; Colin, M.; Potier, P. C. R. Acad. Sci. Paris 1984, 299 , 4177.), 50 mg, 0.056 mM. The resultant solution is treated with 4-dimethylaminopyridine (5 mg, 0.04 mM) and 1,3-dicyclohexyl carbodiimide (18 mg, 0.087 mM) and then heated to 75°C (25 min). TLC analysis after 15 minutes heating shows the reaction to be complete. The precipitated dicyclohexyl urea is filtered off. The filtrate is coated on silica gel (1 g) and chromatographed over silica gel (10 g), which is eluted with EtOAc-hexane (30-70). Fractions of 4 mL are collected, analyzing them by TLC. Fractions 16-42 contain the product and are combined and evaporated under vacuum. This produces 7,10-bis-Troc-baccatin III-13-(4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester ( 9BbC ) as a white solid. TLC (silica gel 60): 40% EtOAc-60% hexane; R f : 0.56 Mass Spec (FAB, m / z ) 1304,1306, 1308 (M+H), 1204, 875, 683, 384, 328 284, 105 (base), 57. 1 H NMR (CDCl 3 ; TMS): δ 1.07 (s, 3H); 1.14 (s, 3H); 1.22 (s, 3H)'; 1.79 (s, 3H); 2.56 (m, 1H); 3.79 (d, 1H); 3.81 (s, 3H); 3.89 (s, 3H); 4.08 (d, 1H); 4.25 (d, 1H); 4.54 (d, 1H); 4.59 and 4.88 (2d, 2H); 4.78 (s, 2H); 4.89 (bt, 1H); 5.43(m, 1H); 5.50 (m, 1H); 5.62 (d, 1H); 6.05 (bs, 1H); 6.12 (s, 1H); 6.47 (d, 1H); 6.49 (s, 1H); 6.75 (bs, 1H); 7.21. (m, 1H); 7.35-7.53 (m, 7H); 7.62 (t, 1H); 8.01 (d, 2H). Preparation 17 : Preparation of 7,10-bis-Troc-13-(N-Boc-β-phenyl isoserinyl)-baccatin III (10BC). Acetyl chloride (0.071 mL, 80 mg, 1.0 mM) is added to methanol (10 mL) and the solution allowed to stand for 30 minutes, giving a 0.1 N HCl solution. 7,10-Bis-Troc-baccatin III-13-(4S,5R)-N-Boc-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester (Preparation 16; 9BbC) (73 mg, 0.056 mM) is dissolved in the above methanolic HCl solution (0.553 mL) and allowed to stand (25 min). The reaction is then diluted with EtOAc and washed with 5% sodium bicarbonate. The layers are separated and the aqueous layer reextracted with EtOAc. The organic phases are combined, dried over sodium sulfate and evaporated under vacuum. The crude product is coated on silica gel (1 g) and chromatographed over silica gel (10 g). The column is eluted with 20% EtOAc-80% toluene. Fractions of 4 ml are collected, analyzing them by TLC. Pure product is found in fractions 10-20 which are combined and evaporated. Impure product in fractions 7-9, is rechromatographed as above. Fractions 11-26 contained the pure product and are combined with pure product from the first column. This gives 7,10-bis-Troc-13-(N-Boc-β-phenyl isoserinyl)-baccatin III ( 10BC ) as a white solid. TLC (silica gel 60): 30% EtOAc-70% toluene; R f : 0.59; the side product 2,4-dimethoxy benzaldehyde runs just ahead of product and right where starting material comes. Mass Spec (FAB, m / z ) 1156, 1158, 1160 (M+H), 1100, 1056, 701, 685, 105 (base), 57. 1 H NMR (CDCl 3 ; TMS): δ 1.20 (s, 3H); 1.27 (s, 3H); 135 (s, 9H); 1.85(s, 3H); 1.95 (s, 3H); 2.35 (s, 3H); 3.41 (d, 1H); 3.90 (d, 1H); 4.17 (d, 1H); 4.33 (d, 1H); 4.60 and 4.92 (2d, 2H); 4.62 (bs, 1H); 4.78 (s, 2H); 4.95 (d, 1H); 5.26 (bd, 1H); 5.42 (bd, 1H); 5.54 (dd, 1H); 5.69 (d, 1H); 6.21 (t, 1H); 6.24 (s, 1H); 7.12-7.42 (m, 6H); 7.49 (t, 2H); 7.62 (t, 1H); 8.09 (d, 2H). Preparation 18 : Preparation of 7-(2,2-dichloroethoxycarbonyl)-13-(N-Boc-β-phenyl isoserinyl)-baccatin III ( 10BD ), 10-(2,2-dichloroethoxycarbonyl)-13-(N-Boc-β-phenyl isoserinyl)-baccatin III ( 10BE ), and 13-(N-Boc-β-phenyl isoserinyl)-baccatin III ( 10BF , Taxotere) 7,10-Bis-Troc-13-(N-Boc-β-phenyl isoserinyl)-baccatin III (Preparation 17; 10BC ) (48 mg, 0.041mM) is stirred at room temperature under nitrogen in 90% MeOH-10% HOAc (3 mL) and the solution treated with activated zinc (85 mg). After 30 minutes reaction a cloudiness occurs. One mL more of the MeOH-HOAc solution is added and the reaction becomes clear. TLC after 30 and 60 minutes look very similar, namely no starting material and two minor and one major more polar products. After 70 minutes reaction, the solid zinc is filtered off. The filtrate is evaporated under vacuum. The residue is partitioned between methylene chloride and water. The layers are separated and the aqueous layer re-extracted with methylene chloride. The organic layers are again washed with water, dried over sodium sulfate, combined and evaporated under vacuum. The crude product mixture is coated on silica gel (1 g) and chromatographed over silica gel (5 g). The column is eluted with EtOAc-hexane (100 mL each of 40-60, 50-50, 60-40, and 70-30). Fractions of 4 mL are collected, analyzing them by TLC. The following fractions are combined and evaporated. Fr. 12-24, 10BD Fr. 29-42, 10BE Fr. 48-84, 10BF Data for 10BD: TLC (silica gel 60): 60% EtOAc-40% hexane; R f : 0.92 Mass Spec (FAB, m / z ) 948, 950, 952 (M+H), 892, 848, 830, 667, 649, 105 (base), 57. 1 H NMR (CDCl 3 ; TMS): δ 1.09 (s, 3H); 1.23 (s, 3H); 1.34 (s, 9H); 1.86(s, 3H); 1.89 (s, 3H); 2.04 (m, 1H); 2.29 (d, 2H); 2.39 (s, 3H); 3.4 (bs, 1H); 3.99 (d, 1H); 4.05 (s, 1H); 4.20 (d, 1H); 4.33 (d, 1H); 4.48 (m, 2H); 4.62 and 4.93 (2d, 2H); 530 (m, 1H); 5.37 (s, 1H); 5.46 (d, 1H); 5.68 (d, 1H); 5.83 (t, 1H); 6.21 (t, 1H); 7.3-7.45 (m, 6H); 7.50 (t, 2H); 7.62 (t, 1H); 8.10 (d, 2H). Data for 10BE: TLC (silica gel 60): 60% EtOAc-40% hexane; R f : 0.65. Mass Spec (FAB, m / z ) 948, 950, 952 (M+H), 892, 848, 667, 527, 509, 105 (base), 57. 1 H NMR (CDCl 3 ; TMS): δ 1.16 (s, 3H); 1.27 (s, 3H); 1.33 (s, 9H); 1.70 (s, 3H); 1.89 (s, 3H); 2.39 (s, 3H); 2.57 (m, 1H); 3.40 (d, 1H); 3.75 (d, 1H); 4.17 (d, 1H); 433 (d, 1H); 4.35 (m, 1H); 4.56 (dd, 2H); 4.64 (m, 1H); 4.95 (d, 1H); 5.28 (m, 1H); 5.37 (d, 1H); 5.68 (d, 1H); 5.92 (d, 1H); 6.15 (s, 1H); 6.25 (t, 1H); 7.20-7.45 (m, 6H); 7.50 (t, 2H); 7.64 (t, 1H); 8.10 (d, 2H). Data for 10BF: TLC (silica gel 60): 60% EtOAc-40% hexane; R f : 0.23. Mass Spec (FAB, m / z ) 808 (M+H), 790, 752, 708, 527, 509, 345, 327, 105 (base), 57. 1 H NMR (CDCl 3 ; TMS): δ 1.12 (s, 3H); 1.23 (s, 3H); 1.33 (s, 9H); 1.74 (s, 3H); 1.84 (s, 3H); 2.37 (s, 3H); 2.56 (m, 1H); 3.60 (bs, 1H); 3.89 (d, 1H); 4.18 (d, 1H); 4.21 (m, 1H); 4.30 (d, 1H); 4.32 (s, 1H); 4.62 (bs, 1H); 4.94 (d, 1H); 5.23 (s, 1H); 5.28 (bs, 1H); 5.54 (d, 1H); 5.66 (d, 1H); 6.20 (t, 1H); 7.25-7.45 (m, 6H); 7.50 (t, 2H); 7.61 (t, 1H); 8.09 (d, 2H). Preparation 19 : Preparation of (2R,3S)-N-carbobenzyloxy-β-phenyl isoserine methyl ester (3C) A solution of (2R,3S)-β-phenyl isoserine methyl ester (2) (Preparation 1, 2 mM) in pyridine containing a small amount of DMAP is cooled in an ice bath and treated with benzyl chloroformate (0.8 ml). After stirring at room temperature overnight, the reaction is diluted with ethyl acetate, washed with 5% aqueous sodium bisulfate, dried and evaporated. The product is obtained pure by silica gel chromatography in ethyl acetate-hexane mixtures. Mp 120-121°C. NMR(CDCl 3 , TMS): δ 3.26 (m, 1H); 3.79 (s, 3H); 4.47 (m, 1H); 5.06 (m, 2H); 5.27 (d, 1H); 5.75 (m, 1H); 7.20-7.50 (m, 10 H). Preparation 20 : Preparation of (4S,5R)-N-Carbobenzyloxy-2-(2,4-dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid methyl ester 5Cb N-Carbobenzyloxy-β-phenyl isoserine methyl ester (Preparation 19, 3C, 0.375 g, 1.14 mM) is dissolved in dry THF (10 mL) and the solution treated with 2,4-dimethoxy benzaldehyde dimethyl acetal (4, 0.300 g, 1.42 mM) and pyridinium p-toluenesulfonate (10 mg) and the solution heated to distill off the THF and methanol. After 1/2 the THF is distilled off, THF (10 mL) is added and the reaction distilled to 1/2 volume again. The process is repeated three times. The reaction is then concentrated in vacuo and the residue chromatographed over 75 g silica gel packed and eluted in acetone-hexane (300 mL of 20-80 and 300 mL of 25-75). Fractions of 20 mL are collected and analyzed by TLC. The following fractions are combined and evaporated under vacuum. Fr. 26-44, 543 mg, isomer 5Cb (other runs have shown this to be the more polar isomer). Data for 5Cb: TLC: silica gel; 20% acetone-80% hexane; R f : 0.19. 1 H NMR (CDCl 3 ; TMS): 8 3.51 (bs, 3H); 3.81 (bs, 6H); 4.56 (d, 1H); 4.8 (bd, 1H); 4.94 (d, 1H); 5.54 (d, 1H); 6.4 (bs, 2H); 6.78 (d, 3H); 7.05-7.50 (m, 9H). Preparation 21 : Preparation of (4S,5R)-N-CBZ-2-(2,4 dimethoxyphenyl)-4-phenyl-5-oxazolidine carboxylic acid potassium salt. 6Cb (4S,5R)-N-CBZ-2-(2,4 dimethoxyphenyl)-4-phenyl-5-oxazolidine carboxylic acid methyl ester (Preparation 20, 5Cb, 444mg,0.93mM) is dissolved in 10ml methanol. To the solution is added water (400µl) and potassium carbonate (200mg, 1.45mM). After stirring overnight no solids remain and TLC indicates very little methyl ester remaining. The solvent is concentrated in vacuo and water (20ml) added to the oil. The solution is freeze dried leaving 638mg fluffy white powder which contains 466mg of the potassium salt 6Cb. TLC: silica gel 60; 1:4 EtOAc:Toluene; R f : origin. Preparation 22 : Preparation of 7-Triethylsilyl-Baccatin III-13-(4S,5R)-N-CBZ-2-(2,4 dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ester. 9CbA Crude (4S,5R)-N-CBZ-2-(2,4 dimethoxyphenyl)-4-phenyl-5-oxazolidine carboxylic acid potassium salt (6Cb, Preparation 21; 75mg,0.11mM) is partitioned between CH 2 Cl 2 and 5% NaHSO 4 solution. The layers are separated and the aqueous layer extracted with EtOAc. The combined organic layers are filtered through anhydrous sodium sulfate and concentrated in vacuo leaving 51mg of (4S,5R)-N-CBZ-2-(2,4 dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid ( 7Cb ). 7-Triethylsilyl-baccatin III ( 8A, 50mg, 0.07 mM) is dissolved in 700pL toluene. All of the (4S,5R)-N-CBZ-2-(2,4 dimethoxyphenyl)-4-phenyl-5-oxazolidinecarboxylic acid is added in a solution of CH 2 Cl 2 . To the solution is added DCC (25mg, 0.11 mM) and DMAP (4mg, 0.04mM) and the solution heated to 80°C driving off the CH 2 Cl 2 . The reaction is checked by TLC and after 1.5 hours very little 7-triethylsilyl-baccatin III is seen. The reaction is allowed to cool and the slurry filtered. The filtrate is concentrated in vacuo and chromatographed over 7gm of silica gel packed in 1:3 EtOAc:Hexane. The column is eluted with 40mL 1:3 EtOAc:Hexane and 75ml 1:2 EtOAc:Hexane collecting 3ml fractions. The desired product is found in fractions 17-32. Mass Spec (FAB-High Res.) Theory: 1146.4882 Found: 1146.4915 1 H NMR (CDCl 3 ; TMS): δ 0.51-0.59 (m,6H); 0.88-0.94 (m); 1.13 (s,3H); 1.18 (s,3H); 1.79-1.89 (m,1H); 2.17 (s,3H); 2.40-2.50 (m1H); 3.67 (d,1H); 3.80 (br s,6H); 4.07 (d,1H); 4.22 (d,1H); 4.39 (m,1H); 4.54 (d,1H); 4.77 (d,1H); 4.86 (d,1H); 4.94 (d,1H); 5.54 (d,1H); 5.61 (d,1H); 5.90 (m,1H); 6.33 (s,1H); 6.43 (m,2H); 6.78 (m,3H); 7.12-7.21 (m,4H); 7.38-7.50 (m,7H); 7.59 (m,1H); 8.01 (d,2H)

Claims: A compound of the formula wherein R 1 is selected from -CH 3 , -C 6 H 5 or phenyl substituted with one, 2 or 3 C 1 -C 4 alkyl, C 1 -C 4 alkyl, C 1 -C 3 alkoxy, halo, C 1 -C 3 alkylthio, trifluoromethyl, C 2 -C 6 dialkylamino, hydroxy or nitro, 2-furyl, 2-thienyl, 1-naphthyl, 2-naphthyl and 3,4-methylenedioxyphenyl; R 11 is phenyl substituted with -(OC 1 -C 2 alkyl) n where n is 1 to 3; and R 12 is selected from -C(O)H, -C(O)C 1 -C 10 alkyl, -C(O)phenyl substituted with one, 2 or 3 C 1 -C 4 alkyl, C 1 -C 3 alkoxy, halo, C 1 -C 3 alkylthio, trifluoromethyl, C 2 -C 6 dialkylamino, hydroxy ornitro, -C(O)C(CH 3 )=CHCH 3 , -C(O)OCH 2 phenyl, -SO 2 -4-methylphenyl, -C(O)(CH 2 ) 3 COOH, -C(O)-4-(SO 3 H)phenyl, -C(O)-1-adamantyl, -C(O)O-3-tetrahydrofuranyl, -C(O)O-4-tetrahydropyranyl, -C(O)NHC 1 -C 10 alkyl, -C(O)NHPh, -C(O)NHPh substituted with one, 2 or 3 C 1 -C 4 alkyl, C 1 -C 3 alkoxy, halo, C 1 -C 3 alkylthio, trifluommethyl, C 2 -C 6 dialkylamino or nitro, or -C(O)C 3 -C 8 cycloalkyl, -C(O)C(CH 3 ) 2 CH 2 Cl, -C(O)-1-phenyl-1-cyclopentyl, -C(O)-1-methyl-1-cyclohexyl or -C(S)NHC(CH 3 ) 3 ; and R 6 and R 14 are the same or different and are selected from -C(O)C 1 -C 6 alkyl, -C(O)OC 1 -C 6 alkyl, -C(O)OCH 2 CX 3 where X is halo, or -C(O)OCH 2 CH 2 SiR 20 or -Si(R 20 ) 3 , where R 20 is C 1 -C 6 alkyl. A compound of Formula 5 wherein R 1 , R 11 and R 12 are as defined in claim 1; and R 9 is C 1 -C 6 alkyl. A compound of Formula 7 wherein R 1 , R 11 and R 12 are as defined in claim 1. A compound according to any of claims 1 to 3, wherein R 1 is -C 6 H 5 and R 12 is -C(O)OCH 2 phenyl. A compound according to any of claims 1 to 3, wherein R 12 is -C(O)NHC(CH 3 ) 3 . A compound according to any preceding claim, wherein R 11 is phenyl substituted with -OCH 3 in the ortho and para positions. A process for preparing a compound according to claim 2, which comprises reacting a corresponding hydroxy-amine of Formula 3 wherein R 2 is H, -NHC(O)H, -NHC(O)C 1 -C 10 alkyl, -NHC(O)Ph optionally substituted with one, 2 or 3 C 1 -C 4 alkyl, C 1 -C 3 alkoxy, halo, C 1 -C 3 alkylthio, trifluoromethyl, C 2 -C 6 dialkylamino, hydroxy or nitro, -NHC(O)C(CH 3 )=CHCH 3 , -NHC(O)OCH 2 phenyl, -NHSO 2 -4-methylphenyl, -NHC(O)(CH 2 ) 3 COOH, -NHC(O)-4-(SO 3 H)phenyl, -NHC(O)-1-adamantyl, -NHC(O)O-3-tetrahydrofuranyl, -NHC(O)O-4-tetrahydropyranyl, -NHC(O)OC 1 -C 10 alkyl, -NHC(O)NHC 1 -C 10 alkyl, -NHC(O)NHPh optionally substituted with one, 2 or 3 C 1 -C 4 alkyl, C 1- C 3 alkoxy, halo, C 1 -C 3 alkylthio, trifluoromethyl, C 2 -C 6 dialkylamino or nitro, -NHC(O)C 3 -C 8 cycloalkyl, -NHC(O)C(CH 3 ) 2 Cl, phthalimido, -NHC(O)-1-phenyl-1-cyclopentyl, -NHC(O)-1-methyl-1-cyclohexyl or -NHC(S)NHC(CH 3 ) 3 ; and R 3 is H, -NHC(O)phenyl or -NHC(O)OC(CH 3 ) 3 ; with the proviso that one and only one of R 2 and R 3 is H; with (1) a benzaldehyde of Formula 4 or (2) an acetal of Formula 4A where n is 1-3. A process according to claim 7, wherein the benzaldehyde is 2-methoxybenzaldehyde, 3-methoxybenzaldehyde, 4-methoxybenzaldehyde, 2,4-dimethoxybenzaldehyde, 3,5-dimethoxybenzaldehyde, 2,5-dimethoxybenzaldehyde, 2,4,6-trimethoxybenzladehyde, 4-ethoxybenzaldehyde or 4-methoxybenzaldehyde. A process according to claim 7, wherein the hydroxy-amine of Formula 3 is reacted with 2,4-dimethoxybenzaldehyde dimethyl acetal. A process of preparing a compound according to claim 1, which comprises reacting a compound according to claim 3 with a baccatin compound of Formula 8 wherein R 6 and R 14 are as defined in claim 1; in the presence of a dehydrating agent.

Inventors: JOHNSON ROY A, KELLY ROBERT C, NIDY ELDON G, SKULNICK HARVEY I, JOHNSON, ROY A., KELLY, ROBERT C., NIDY, ELDON G., SKULNICK, HARVEY I.
Applicants: UPJOHN CO, PHARMACIA & UPJOHN COMPANY
Application year: 1994
Main classification: C07D305
IPC codes: C07D263, C07D405, C07D409, C07D305, C07F7, C07D407, C07D413